The anchor prediction model \(P_a\)  considers the given sentence \(\mathbf {s}_i\)  and reasons through prior article context to find the most likely sentence where a QUD can be generated, such that \(\mathbf {s}_i\)  is the answer. Since this
task involves long document contexts,
we use the Longformer model (longformer-base-4096) [1]}, shown to improve both time efficiency and performance on a range of tasks with long contexts.
